1. Field of the Invention
This invention relates to an image processing apparatus, and more particularly, to an apparatus which can easily perform registration of a plurality of digital fundus (eyegrounds) images before performing image processing, such as addition, subtract;ion or the like, of the images.
2. Description of the Prior Art
Heretofore, in order to satisfy the requirements to observe the mutual positional relationship among blood vessels, hemorrhages (bleeding) , vitiligo, and the like on a retina, a fundus photograph over a wide angle of view has been prepared by adding a plurality of fundus photographs so that the positional relationship among the respective photographs coincides with one another in up and down, right and left, and oblique directions.
Recently, with the progress of image processing techniques, synthesis of digital images has been performed by inputting fundus images using a general-purpose image processing apparatus, and utilizing image processing techniques, such as the affine transformation and the like.
Furthermore, a technique has been disclosed in Japanese Patent Public Disclosure (Kokai) Nos. 64-23677 (1989) and 62-140172 (1987), in which see-through synthesis of a plurality of images is performed for a plurality of stored image data using address generation means.
However, in conventional techniques utilizing analog images, it takes time until a fundus photograph is developed, printed, and the like.
Even in conventional techniques utilizing digital images, it is difficult to perform an exact synthesis, since a synthesis must be performed according to information around a boundary (the hatched portion) between, for example, fundus images 19 and 20 shown in FIG. 12.
Furthermore, there is also a disadvantage in conventional techniques in that each image is distorted due to the fundus camera, and deviation thereby occurs at numeral 21 in FIG. 13. Hence, it is difficult to exactly adjust the images.
Moreover, when the address generation means as shown in the above-described Disclosures is used, there is a disadvantage in that address control becomes complicated when a plurality of images are synthesized in a state in which the images are rotated relative to one another.